Hold-down slip assembly



March 11, 1952 A. 1.. STONE HOLD-DOWN SLIP ASSEMBLY Filed Feb. 19, 1948IN VEN TOR.

Patented Mar. 11, 1952 HOLD-DOWN SLIP ASSEMBLY Albert L. Stone, RedondoBeach, Calif., assignor,

by mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware Application February 19, 1948, Serial No.9,600

2 Claims. (01. 25523) The present invention is directed to a slipassembly for holding sections of pipe.

In the handling of sections of pipe in drilling operations it is oftendesirable or necessary to hold the sections against downward androtative movement. At the present time most wells for producingpetroleum and gas are drilled by the rotary drilling method whichinvolves the use of a rotary table for producing rotative motion of thedrill stem. The drill stem is constructed by fastening sections of pipetogether by means of screw threads. Incidental to the actual drillingoperation it is necessary to add sections of pipe to and remove sectionsof pipe from the drill stem and in this operation it is common tosupport the drill stem by using a slip assembly mounted on a masterbushing which in turn is carried by the rotary table.

It is necessary to support the drill stem below the joint to be made upor broken out when adding or removing sections of pipe. The operation ofattaching or removing a section of pipe by screwing or unscrewing ajoint requires that the pipe on one side of the joint be held againstrotative movement while the pipe on the other side of the joint isrotated.

It is common to use a slip assembly for holding the drill pipe againstvertical movement in such operations. The slip assembly usually consistsof a member called a slip bowl which defines a cavity having sidestapering upwardly and outwardly. Cooperating and fitting within the slipbowl are slip members having outer surfaces tapering downwardly andinwardly with the several members cooperating to define a centralpassage. The slip members are provided with die members adjacent thecentral passage for gripping a section of pipe.

When a section of pipe is supported from the slip members the weight ofthe pipe exerts a force having components directed radially outwardly aswell as downwardly.

When a conventional slip assembly is supporting a section of pipe, theapplication of a rotative force between the section of pipe and the slipbowl will produce a horizontal component directed radially outwardly anda vertical component directed upwardly. It will be evident that in aconventional slip assembly the slip assembly cannot be used to preventrotative movement between the suspended pipe and the slip bowl unlessthe weight of the pipe is such that the vertical downward componentexerted by the pipe on the wedge surface of the slip members is greatenough to overcome the upward component produced by the rotative force.For this reason it is impossible to use conventional slip assemblies tohold a back up or to transmit rotative movement to a section of pipewhen breaking out or making up a joint unless the section of pipesuspended from the slips has a weight greater than a certain minimum.When breaking-out joints of pipe in rotary drilling operations, it isconventional to use a tong on each side of the joint for the entiredrill stem and when making up joints of pipe it is conventional to use atong to hold a back up until the weight of the drill stem becomessuflicient to allow the use of the slips for this purpose.

It is an object of the present invention to provide an arrangement forholding a section of pipe against downward movement and against rotativemovement. More particularly, it is an object of the present invention toprovide a slip assembly provided with a positive locking means forholding the slip sections in position whereby the slip assembly may beused for holding sections of pipe against vertical and rotative movementwith respect to the rotary table when breaking out and making up jointsof pipe.

The deviceof the present invention may be briefly described as includinga slip bowl anchored a ainst a vertical movement, as by mounting it in arotary table, slip members arranged to fit within the slip bowl andprovided with die members for gripping a section of pipe and a cammember secured against vertical movement and adapted to lock releasablythe slip members against upward movement in the bowl.

The present invention will now be described in greater detail inconjunction with the drawing in which:

Fig. 1 is a plan view of a slip assembly embodying the presentinvention;

Fig. 2 is an elevation, partly in section, of the device shown in Fig. lwith a section of pipe gripped thereby;

Fig. 3 is a view taken along lineIII-III of Fig.2;

Fig. 4 is a fragmentary section taken along line IVIV of Fig. 2;

Fig. 5 is the device shown in Fig. 4 in a different position;

Fig. 6 is an elevation showing an embodiment of the present invention;and

Fig. 7 is a view showing a single die element to illustrate theconstruction thereof.

Turning now specifically to they drawing, a rotary table A define acentral passage, the lower portion of which is defined by a cylindricalwall H and the upper portion is a wall l2 square in configuration withthe two wall portions connected by upwardly facing surface or shoulderl3.

A slip bowl member or master bushing B has its outer surface fittingslidably within the central passage defined by rotary table A, that isto say, its lower outer surface is cylindrical and its upper portion isin the shape of a square head which sets within member A and issupported from shoulder I3. Slip bowl B defines a central passage I4with the surface l5 which defines the upper portion of the passagetapering upwardly and outwardly for receiving the slip member assembly.

Slip members C are adapted to set within the slip bowl. Each member Cincludes a body I6 having an outer arcuate surface I! and an innerarcuate surface IS. The upper portion of each body i defined by ahorizontal surface l9 and a wedge surface 20 which tapers outwardly anddownwardly to join surface IS with surface I1.

In the drawing, the slip bodies I6 occupy an arc of approximately 120 sothat three slip assemblies C may be arranged within the slip bowl andwhen so arranged the surfaces 8 define a central passage for receiving asection of pipe.

Die members 2| are mounted on each body l6 for gripping the pipe to beretained by the assembly. Each die member is pivoted to the slip bodywith a lower pivot 22 extending into a suitable opening provided in slipbody [6 and an upper pivot 23 extending into an opening of plate 24which, in turn, may be secured to body l6 by any suitable means such asscrews 25.

For convenience, the arrangement of the slip assembly C whereby diemembers 2| may be pivoted when a rotative force is exerted on a sectionof pipe engaged by the slip assembly is designated as self-energizingbecause the application of a rotative force between the slip bowl and asection of pipe supported by the assembly causes an increased force tobe exerted against the pipe by the dies.

In Fig. 2, a section of pipe 26 is shown supported from the slipassembly.

The several slip assemblies C are provided with interlocking means sothat the members will move vertically as a unit. In the drawing, theinterlocking means are provided by a laterally extending projection 21extending from the side of each body I6 which, in turn, fits into amating opening 28 defined by the edge of the slip body l6 adjacent theprojection 21. With this arrangement the slip assemblies C are raisedand lowered as a single unit. It will be understood that the movement ofthe slips vertically may be provided manually or by suitable mechanicalmeans but since the means for moving the slip assemblies C verticallydoes not in itself form a part of the present invention, such a meanshas not been shown in the drawing.

It is a feature of the present invention that the component of forcesdirected vertically upwardly when a rotative force is exerted betweenslip members C and 'slip bowl B is resisted by releasable locking means.In the embodiment shown in the drawing, the releasable locking means isdesignated as D and includes a housing 29 secured to the rotary table Aby suitable means such as cap screws 30. Housing 29 defines a passage,rectangular in shape, in which is slidably arranged a movable cam member3| The outer surface of the cam member is generally rectangular in shapewhich allows it to move slidably withinhousing 29 but the end of theundersurface thereof defines a slanting or wedge surface 32. Cam member3| defines a central cylindrical cavity in which piston 33 is slidablyarranged. Piston 33 is attached to piston rod 34 which, in turn, issecured to housing 29.

A packing 35 is mounted on the piston to prevent leakage between theexterior surface thereof and the wall of cam member 3|. Another packing36 is provided around piston rod 34 to prevent leakage around the pistonrod. The portion of the cavity defined by member 3| between the pistonand packing 36 is designated as 31 while the portion of the cavity tothe right of the piston is designated as 38. Piston rod 34 defines acentral passage communicating with cavity 38 and connected throughconduit 39 to a suitable source of hydraulic pressure, not shown. Cammember 3| defines a side port 40 connecting with cavity 37 and connectedthrough conduit 4| to a suitable source of fluid pressure not shown.

It will be seen that by exerting pressure in cavity 38 while releasingpressure from cavity 31, the cam member 3| may be pushed toward thecenter of the slip assembly to force wedge surface 3| thereof intocontact with surface 20 of slip assembly C. With the two wedge surfacesin contact, the fluid pressure exerted against cam member 3| biases amember C downwardly and this bias is transmitted by the interlockingmeans previously described to the adjacent members C, the three memberscooperating to exert a downward component for resisting the upwardcomponent resulting when a rotative force is exerted between bowl B andpipe 23.

In normal operation of the device movement of cam member 3| radiallyaway from the center line of the assembly releases slip assembly C sothat these assemblies may be moved upwardly and outwardly, this, forexample, will allow tool joints to be passed down through slipassemblies. When it is desired to support a section of pipe, the slipassemblies C are allowed to drop downwardly with the surface I5 of theslip bowl contacting surfaces I! of the slip bodies to move the slipbodies radially inwardly as they move downwardly so that die members 2|contact the section of pipe to be suspended. If the slips are to be usedto prevent relative rotative mo tion between the suspended section ofpipe and slip bowl B, the members C are then looked downwardly byforcing cam member 3| inwardly so that its wedge surface 3| biasesagainst slanting surface 2|! of a slip body I6. Upon exerting relativeforce between the section of suspended pipe and slip bowl B, the diemembers 2| move arcuately on their pivots so that the edges thereof bitemore deeply into the section of pipe to increase the gripping exerted bythe die members. As heretofore explained, this rotative force exerts acomponent against body l6 of assembly C, this component being directedvertically upwardly. This vertical upward component is resisted by cammember 3| and as long as the cam member resists this force, the slipassembly holds the pipe against relative rotative movement as well asrelative downward movement.

While I have described a single embodiment of the present invention, itwill be obvious to a workman skilled in the art that various changes maybe made without departing from the scope thereof. For example, in thedrawing, a single releasable locking means D is shown for locking theslip assembly C in position to resist the upward vertical componentexerted against assemblyv C upon relative rotative motion between asection of pipe engaged by the assembly and the slip bowl B. It will beobvious that if de- 1. A device for releasably holding a section of pipecomprising, in combination, a rotary table for a drilling rig, a slipbowl carried by the rotary table, a plurality of self-energizing slipmembers, each member having at least one die section mounted forindependent rocking movement to present a portion of its pipe grippingedge inwardly of its normal position for pipe gripping purposes, saidmembers being withdrawable from the slip bowl and arranged to fit intothe slip bowl for holding a section of pipe against downward and angularmovement, a housing secured to the upper surface of said rotary table, acam member having a cam surface slidably carried by said housing forhorizontal movement and arranged to move into a first position with itscam surface in contact with a cooperating surface of one of the slipmembers to lock said slip in position against upward movement andmovable from the first to a second position out of contact with saidslip member, said housing and said cam member cooperating to form apiston and cylinder assembly and a conduit for fluid operativelyconnected to said housing whereby the cam member may be moved from oneto the other of its positions by fluid pressure.

2. A device for releasably holding a section of pipe comprising, incombination, a rotary table for a rotary drilling rig, a. slip bowlcarried by the rotary table, a plurality of self-energizing slipmembers, each member having at least one die section mounted forindependent rocking movement to present a portion of its pipe grippingedge inwardly of its normal position for pipe gripping purposes, saidmembers being withdrawable from the slip bowl and arranged to fit intothe slip bowl for holding a section of pipe against downward and angularmovement, a housing with a passage having its axis making substantiallya right angle with the path of withdrawal of a slip member secured tothe upper surface of said rotary table, a locking member having a wedgesurface slidably arranged for horizontal movement in said passage of themounting member and arranged to move to a first locking position withits wedge surface in contact with a cooperating surface of one of theslip members to lock said slip in position against upward movement andmovable from the first position to a second position out of contact withsaid slip member, and said housing and said looking member cooperatingto form a piston and cylinder assembly and a conduit for fluidoperatively connected to said housing whereby the locking member may bemoved from one to the other of its positions by fluid pressure.

ALBERT L. STONE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,400,940 Clarke Dec. 20, 19211,556,094 Fletcher Oct. 6, 1925 1,560,701 Layton Nov. 10, 1925 1,650,101Taylor Nov. 22, 1927 1,973,809 Heggem Sept. 18, 1934 2,076,042 Peniok eta1 Apr. 6, 1937 2,231,923 Koen Feb. 18, 1941 2,287,432 Kinzbach June 23,1942

